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ON THE OPTIMIZATION OF THE AFT-PART OF FINE HULL FORMS

The optimisation of the aft-part of fine hull forms was investigated, following the optimisation of overall performance of the rudders. The optimisation studies of rudder configurations and stern-end-bulb suggest that the aft-part of hull forms of merchant ships lends itself to further improvement. The main aims were to clarify the potential interactions between the hull and the propeller, through theoretical and experimental research, and to develop a new method of designing the aft-part by presently available theories. This involved a method of calculation of thrust deduction by the double model flow theory, Lagalley's theorem, and pressure integration, which were applied to a model container ship and a modified hull form design. Simultaneous improvements of thrust deduction and wake fraction were indicated. A new method of calculation of inviscid resistance of propelled ships was also developed. This is based on the linear wave-making theory, in which singularities are distributed on the hull surface together with the propeller disc plane. This method was proven to be effective in the theoretical elucidation of thrust deduction and in calculation of the inviscid resistance of propelled ships. The wave-effect must also be considered in the evaluation of thrust deduction in medium- and high-speed ships. Order from BSRA as No. 54,724.